After the royal placed the medal around the neck of Sergeant Elizabeth Marks, she publicly asked him to return it to Papworth Hospital in Cambridge, which had provided the combat medic with critical care.

The UK swimming team won a clutch of medals during the fourth day of the games, being staged in Orlando, Florida, but the heartfelt gesture from the American captured the imagination of the crowds.

On the eve of the first games in 2014 Sgt Marks, 25, from Arizona, became gravely ill when she collapsed with a serious lung condition and was put into an induced coma.

Sgt Marks handed her medal back to the prince (Image: Splash News)

She said: "I landed in London and became very ill very rapidly, I was in hospital in London and went into respiratory distress syndrome, they shipped a team down from Papworth who put me on to ECMO (extracorporeal membrane oxygenation) life support and that ultimately saved my life.

"And when they did so I was on it for 10 days and ended up waking in an army hospital in Germany having no idea what had happened.

"But they absolutely saved my life and I can't thank the UK enough for having that kind of medical support and taking such good care of me.

"So I gave Prince Harry one of my medals and hope it will find its way back to Papworth."

Fighting back the tears, she paid tribute to the NHS, saying: "Thank you, I'll never be able to repay you, but what you're doing is wonderful."

Sgt Marks, who joined the US army aged 17, suffered a serious hip injury in 2010 which left her with no sensation in her left leg but she has battled back to fitness and still serves in the military.

The pair share a joke (Image: Chris Jackson/PA Wire)

She won all four swimming events she entered at the Invictus Games for injured military and veterans, but decided to give her 100 metre freestyle gold to the hospital as it had been touched by the Prince, she said.

Sgt Marks added: "It's just an honour to be here and stand next to all the other soldiers, I can't think of anything else I'd rather be.

"I was a little apprehensive, I was nervous because of what had happened last time but I was eager to perform and show my team and show the other countries how much I love their support.

"When I came out of my coma to see all the pictures of them supporting me while I was there, without even knowing I was in that state, made me cry like a baby so it was a chance to give something back."

Sgt Marks was struck down by the serious illness just before she competed in the first Invictus Games.

After her success in the pool at the Orlando Games she said she was looking forward to competing in the Paralmypics in Rio this summer in four swimming events.

Sgt Marks competed in the Invictus US swimming team (Image: Chris Jackson/PA Wire)

Harry joined in the celebrations around the water after the UK men's relay quartet, led by national team captain David Wiseman, won gold in the final event to add to a clutch of UK golds bagged by swimmers.

He was part of a five-man group hug and his khaki-coloured shirt was left wet after he embraced the topless swimmers.

Earlier the prince had found time to visit the famous Walt Disney World attraction - returning to a ride he enjoyed with Diana, Princess of Wales.

Harry toured the site in Orlando which every year attracts tens of thousands of tourists - many from the UK - and braved the log flume ride of Splash Mountain.

He made his late night trip after he had watched the UK lose a hard-fought sitting volleyball final to America.

Hollywood star Michael J Fox was among the spectators and later he praised the Invictus Games athletes for the "intensity" of their competitive spirit.

The pair shared an emotional moment (Image: Chris Jackson/PA Wire)

He told the Orlando Sentinel: "What is great is the level of competition, the intensity of the athletes, and they're athletes. They're athletes first, and there is obviously this whole other story behind it about bravery and service that they have given us as a country."

The actor who has Parkinson's disease added: "There is always something worth striving for, always something worth achieving, whether it is a personal struggle or outside of a personal struggle."

The Canada-born actor said about Canada hosting the Invictus Games next year: "I think I am going to make an effort to be there.”